"As I pointed out in my previous email, you need 32-bit TIFFs for Prophoto color space. Adobe RGB is about right for 16-bit TIFFs and 16-bit TIFFs are far too small for Prophoto RGB. 32-bit TIFFs do not exist yet.

A Nikon D800E is about high resolution not about capturing huge color spaces.

Thanks for sharing that, it's a much clearer answer than the previous one.

What they are probably referring to is that due to the 'uber' huge Prophoto RGB gamut, the encoding/quantization steps represent pretty large steps in gradients. That's why it is recommended to not use that colorspace with 8-bit/channel images. Using a smaller gamut color space, the quantization steps get smaller, and there is less risk of posterization when applying extreme postprocessing. A 32-b/ch colorspace at least offers a more accurate quantization, a floating-point encoding even more accurate.

I't is a bit puzzling though why they chose to limit themselves to Adobe RGB instead of something with a bit larger gamut like Bruce Lindbloom's Beta RGB (which can accomodate pretty much all important/common colors, but with relatively small quantization step increments, and without an immediate need for chromatic adaptation).

This is very concerning. I'm not sure what prompted the origin of this thread but DxO's response isn't good.

ProPhoto is not too large for 16 bit TIFF files. As far as 32 bit TIFF files not existing, that's flat out wrong. 32 bit TIFF files can be created via HDR software. That's the only 32 bit file type that Lightroom will work with.

ProPhoto is not too large for 16 bit TIFF files. As far as 32 bit TIFF files not existing, that's flat out wrong. 32 bit TIFF files can be created via HDR software. That's the only 32 bit file type that Lightroom will work with.